Gentle skin care. Gentle soap free cleanser, fragrance free products and lots of moisturizer preferably cream or ointment (like vasoline or aquaphor) forms. If needed topical steroids can be used, but best to have baby evaluated by dermatologist for most appropriate regimen.
Eucerin or rx. First, stop all baby soaps and use dove, the white bar, for the bath. After bathing and twice a day, use eucerin cream all over. It is thick and sticky but that is why it works so well. If that is not sufficient, see your pediatrician. Baby may need a prescription steroid cream.